The present invention relates to automated sorting apparatus used to rapidly handle and sort large volumes of documents, and specifically to an apparatus for separating single pieces of so-called "flat mail" from large groups of such mail, even in situations when the mail is randomly collated as to size and type.
Flat mail, or "flats" are terms used to refer to mail other than normal letter-sized mail, and includes magazines, large mail, and thin mailer sheets which are folded over in half, thirds, or quarters, and fastened by a staple, tape, adhesive. Presently, such mail requires a significant amount of handling by Postal Service personnel, due to the inability of commonly available automated mail handling equipment to quickly separate individual pieces of flat mail for reading and subsequent sorting.
Flats, as well as letter-sized mail, are usually fed in horizontal stacks of vertically oriented pieces to automated machinery, which separates or singulates individual pieces from the stack, positions each piece for manual or automatic reading of the Zip Code, and subsequent sorting of each piece to a bin corresponding to the Zip Code or a portion thereof, such as the last three digits. Regardless of whether the reading is done manually or automatically, the separation equipment must properly separate and position each document for fast and efficient reading without jamming. Also, the passage of "doubles", or two pieces temporarily stuck together, through the separation path is to be avoided.
Conventional equipment has the tendency to damage or mutilate certain flat mail during the separation process. For example, folded over pieces and magazine pages are often skewed and torn by being subjected to uneven roller or belt pressures, larger mail pieces are often creased, crumpled or inadvertently folded, and smaller pieces sometimes temporarily adhere to larger ones. These and similar problems of damaged flat mail require frequent manual attention by Postal Service personnel to clear jams caused by mutilated pieces becoming caught in the machine and holding up the sorting process.
Various systems have been proposed for providing trouble-free and rapid automatic separation, singulation, and sorting of flats. One such prior system employs suction cups attached to pivoting arms which grab individual pieces of mail from a vertical stack and pull them across a flat conveyor surface for subsequent reading. Other proposed systems employ vacuum heads, some also provided with specially designed suction cups, to more effectively grab and convey individual pieces of flat mail with minimum damage. However, to date, none of the proposed systems have met the required design parameters of high speed, versatility in handling a wide variety of mail, reliability, ease of operation, and low installation and maintenance costs.
Thus, there is a need for an apparatus which rapidly separates and singulates flat mail with a relatively simple yet effective configuration. There is also a need for such an apparatus which grips mail pieces of all sizes over a substantial surface area of each piece for rapid transmission along the separation path to prevent crimping of the mail piece. There is also a need for such a separator which accommodates pieces of flat mail of varying thicknesses, from thick magazines to single sheets, without jamming. Lastly, there is a need for a flat mail separator which is capable of separating as many as 10,000 pieces of mail per hour.